1. Field of the Invention
This invention relates to remote control apparatus and, more particularly, to novel and highly effective apparatus for remotely controlling the operation of electrical switch means movable between first and second states or conditions.
2. Description of the Prior Art
Electrical switches are movable between a plurality of states or conditions, such as "on" and "off", and often need to be controlled from a remote location. For example, it is hazardous for workers, swimmers or bathers, while in the water or standing on a wet surface, to touch an electrical switch directly in order to control lighting, audio equipment, electrical pumps and other machinery, etc., powered by house current. Persons in such an environment are electrically well grounded, and unless proper precautions are taken, electrocution may result.
One solution that has been proposed in order to enable a worker at an electroplating station or in a culvert or ship bilge or to enable a user of a hot tub or similar facility to control electrical equipment while in the water is to remove the electrical equipment from the vicinity of the water and to establish a pneumatic control link between the worker or user of the facility and the electrical equipment. Since the push button, squeeze bulb or other control device accessible to the worker or user of the facility is not electrical, it can be safely operated by a person in the water.
Conventional devices of this kind have, however, a limited operating range because of the rather large pneumatic impulse required for their operation. In other words, the conventional devices are "stiff" and not easily operated, and the push button or squeeze bulb must be pushed or squeezed vigorously in order to operate the conventional devices, even when they involve only a short pneumatic line between the push button or squeeze bulb and the remote device that operates the electrical switch. In the case where a long pneumatic line is used, operation becomes unreliable or impossible because of attenuation of the pneumatic impulse.
Squeeze bulbs and other non-electrical actuators, alternate action switches, and various linkages between the two are well known in the art. A U.S. Pat. No. 1,354,999 to Pieri discloses a pneumatic bulb which when squeezed causes simultaneous operation of a camera shutter and explosion of a charge of flash powder. Specifically, a pulse of air generated by squeezing a bulb extends an actuater pin, thus raising a plunger against the restoring force of a spring and closing a switch. An electric circuit including a battery, a coil and connecting wires then generates a spark that ignites a powder charge.
A U.S. Pat. No. 4,012,606 to Hutt discloses a switch that comprises plates that are linearly reciprocated by rotary cams under the control of a cam operator and that governs the operation of switches. The plates can be contoured to control the switches in accordance with various programs.
A U.S. Pat. No. 4,150,264 to Lieberman discloses a squeeze bulb that connects through tubing with a piston. When the bulb is squeezed, a pulse of air advances the piston against the force of a restoring spring. A piston rod engages a cam wheel on which a square cam is mounted. The square cam alternately moves a switch spring arm and contact point between closed and open positions.
A U.S. Pat. No. 4,354,074 to Aurand et al. discloses an alternate action key for use on the keyboard of a computer terminal or the like wherein a cam follower on a rotatable, resilient, C-shaped collar tracks in a cam track.
In addition, commercial pneumatic-electric devices are available wherein a pneumatic impulse deforms a diaphragm which then closes an electrical switch. In other commercial devices, a fixed cam controls the movement of a cam follower which is biased against the cam. The biasing force gives rise to friction which reduces the sensitivity of the device.
None of these patents and devices provides a solution to the problem of reliably and easily controlling the operation of electrical equipment from a remote location wherein a user of the equipment is protected against the danger of electrical shock.